The field of the invention is that of ordnance and warhead construction. The present invention relates to fragmentary warhead construction and, in particular, to the construction of warheads using notched fragmenting rods.
In the prior art, most missile fragmentation warheads either use a solid steel case filled with explosive (which is the conventional design) or consist of explosive surrounded by a thin shell with "discrete" fragments glued to the shell which is generally called the discrete fragment design. In either case the warhead is then mounted into the ordnance section where structural loads are carried by a surrounding shroud.
An example of the conventional steel case design is LaRocca, U.S. Pat. No. 3,799,054 filed Mar. 26, 1974. This reference teaches a warhead for controlling the fragmentation of explosive devices having a cylindrical metallic fragmentation casing, wrapped with metallic strips of heavy density to cause fragments to form. This type of construction is limited to ordnance which has a single type of fragment, as the fragments are formed by the metal case. Because the fragmenting section is also load bearing and/or structurally supporting, some fragment materials are precluded. Only those materials which are structurally strong can be used for load bearing elements, thus eliminating many materials that could be used for fragments. In addition, the steel case design either employs heavy materials like LaRocca, or involves complex machining of the warhead case to form the fragments.
An example of discrete fragment design is represented by Brumfield et al., U.S. Pat. No. 3,977,327 filed Aug. 31, 1976. The Brumfield et al. reference is typical of many fragmentation schemes which precut fragments and then must sandwich them between steel or aluminum cylinders which form the case or missile airframe. Construction of this type of warhead is tedious and labor intensive. It is also extremely difficult to manually plane all the fragments in the required matrix pattern with each fragment aligned to precisely form the desired pattern. It is conventional to twist and shake the heavy warhead case to coax each fragment into its proprietary physical position, but gaps and spaces inexorably remain. These irregularities degrade performance and attenuate lethality.
To date, most missile fragmentation warheads use the conventional or discrete fragment design. Both designs have associated advantages and disadvantages. In the conventional design the case is notched or welded to produce the desired fragment break up. The advantages to this design are that it reliably produces uniform size fragments with high velocities, and it is easily produced. One disadvantage to this design is that fragmentation customization is not easily performed. It is inherently difficult (if not impossible) to use fragments of different materials without a performance penalty. Also, changing the fragment size and geometry is not easily accomplished. In contrast, the discrete fragment design allows for easy tailoring of the fragments as fragments of differing materials and geometries are easily utilized, however, this warhead is much more costly to produce as each fragment must be attached to the warhead.
The disadvantages of the conventional design and the discrete fragment design are overcome by the present invention which provides a fragmenting notched rod to replace the discrete fragments used in the discrete fragment type warheads. Each rod replaces a column of fragments constituting up to 100 discrete pieces, thus reducing the labor required for constructing as much as an order of magnitude.